I have a Vetterman exhaust with 2 muffs, but I also have a Superior cold air induction sump, so potentially different. I plumbed my air differently than Vans instructions because of these differences, but Iím happy with the result and do not have cowl interference, though some clearances are close.
Conceptually, from the intake on the ramp, I went through the fuel injection air intake tubes to the back of the sump to a T split, sending intake air to each muff located on separate final exhaust pipes (output of 2-to-1), then each muffís output goes to the separate heater vents.
Vanís installation has muffs in series using heat from 2 of 4 cylinders splitting output air - my installation uses muffs in parallel using heat from 4 of 4 cylinders splitting input air.
RV-14A Builder - kit #136
N314KC - First flight Mar 8, 2017, 24th in the air, >700 hrs
XP-400 Aero Sport Power, replaced with Lyc Thunderbolt 390
Sport Pilot (weight-shift control) - Airborne XT912
Dues paid 9/2020